SI1 (Slightly Included 1)
Inclusions noticeable under 10x; about 60-70% of SI1 diamonds remain eye-clean in brilliant cuts.
SI1 (Slightly Included 1): Inclusions noticeable under 10x; about 60-70% of SI1 diamonds remain eye-clean in brilliant cuts.
SI1 is where careful stone selection becomes essential. In round brilliant cuts under 1.5ct, roughly two-thirds of SI1 stones appear eye-clean. In fancy shapes and larger stones, the rate drops. Always inspect the clarity plot and, where possible, a high-resolution video. When you find an eye-clean SI1, it offers substantial savings over VS2 with no visible compromise.
Standards bodies: GIA
Frequently asked questions
Are SI1 diamonds always eye-clean?
No. This is the grade where inclusions start to sometimes be visible. In round brilliants under 1.5ct, most SI1 stones are eye-clean; in step cuts and larger stones, the rate drops.
How do I tell if a specific SI1 is eye-clean before buying?
Review the clarity plot on the lab report (central inclusions are worse), check a high-resolution video, and consult the retailer's eye-clean guarantee policy.
What's the price advantage of SI1 over VS2?
Typically 15-25% at the same colour, cut, and carat. On large stones the gap widens.
Which shapes hide SI1 inclusions best?
Round brilliant, oval, pear, and marquise. Step cuts (emerald, asscher) and princess are less forgiving.
Does SI1 still certify for insurance?
Yes. Any lab-graded diamond including SI1 and SI2 is fully insurable.
Related terms
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